1. Field of the invention
The instant invention relates to integrated circuits in general and more in particular to integrated audio amplifiers.
2. Description of the prior art
An ever increasing output power is required from battery operated integrated audio amplifiers (car radios, portable radios and recorders, etc.). This has made popular integrated amplifiers capable of operating in a "bridge" configuration and therefore capable in principle to supply to the loudspeaker of the sound reproduction system a maximum peak voltage equal to twice the value of the supply voltage (battery). However, in case of somewhat lower quality apparatuses the single-ended configuration having an output dynamic equal to the supply voltage is still largely utilized. This configuration permits a reduced power dissipation and a reduced number of amplifying stages.
For obvious reasons, manufacturers of these apparatuses favor integrated devices which from one hand require the smallest number of external components and on the other hand have a small size standard package.
Also for the comprehensible reason of simplifying inventories, manufacturers of these apparatuses favor stocking a single type of integrated circuit capable of being connectable in an external circuit and to operate correctly in a bridge or balanced configuration as well as in a single-ended or stereo configuration.
Nowadays there are many integrated circuits capable of allowing the connection of two monolithically integrated amplifiers present in the chip either in a bridge or stereo configuration. These known devices have notably a rather large package because they need a relatively large number of pins in order to permit the connection in a bridge configuration or in a stereo configuration of the two amplifiers integrated therein by means of an appropriate external circuit of the apparatus. Of course unmodifiable bridge configured and stereo configured integrated circuits are available in small, seven pin, packages.